# Oil Friction Measurement?

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#### Dominic

Is there a frictional measurement that can be made on an oil against an oil or against a metal to determine how *slick* it is? Or is this just a matter of how thick it is, i.e. thicker = slicker since it doesnt squish out? But then people say thicker = more friction? Im a little confused, Im also doing organic chemistry homework right now and thats probably why, but it just popped in my head (since I'd rather think about oil than homework) and so Im asking.

#### RB Shannon

I'm not sure how they measure it but I would assume it is through torque.As far as I understand the coefficient of friction is determined by how easily the layers of molecules break their bond from one another and slide under pressure (shear).The easier they shear the less heat.Maybe this link will help,It's in real player 1 Thick Film Lubrication 78 minutes long and rebuffers a lot with a 58k modem but worth it

#### Dominic

quote:
Originally posted by Jay: Viscosity, by definition, is a fluid's internal friction. The higher the viscosity the higher the friction. This site has a good discussion of oil viscosity and how it's measured: http://www.lubrizol.com/LubeTheory/theory.htm#viscosity
Makes sense thanks

#### MolaKule

Staff member
Dominic, Great subject you are studying, stay with it! We need more people on this board with organic chemistry backgrounds. The coefficient of friction f = Tangential force/ normal force, where the tangential force is called the "force to overcome mechanical friction." The normal force is the force perpendicular to the plane of the surface, that is pressing down on the top sliding surface as that surface moves to the right. Mechanical friction between machined surfaces arises primarily from: 1. Adhesion because of molecular attraction, 2. Interlocking of surface irregularities, 3. Chemical and surface reactions. It is because of the viscosity of the oil that that a pressure is created between the two adjoining surfaces. ASTM D5183 Section 11. shows a formula for determining the friction coefficient using the Four-Ball Wear Test Machine.

#### buster

quote:
Im also doing organic chemistry homework right now and thats probably why,
Have fun, my wife just wraped up taking Advanced Organic Chemistry II at Cornell. What a freakin headache for her and me!

#### MolaKule

Staff member
Buster, Could you send me a PM and tell me what text (and ISBN) your wife is using? I need to update since my text was by Morrison and Boyd; not really old but not really new! Thanks. Mola

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